1. Field of the Invention
The present invention relates to a wheel frame for supporting a tire and more particularly, to a wheel frame of the fiber composite material.
2. Description of the Related Art
Taiwan Patent 1329080 discloses a hollow wheel frame for a bicycle. According to this design, the hollow wheel frame defines an outer tire groove for bonding or plug-setting a tire. The inner side of the hollow wheel frame is adapted for the mounting of spokes. By means of the spokes, the hollow wheel frame is connected to a wheel hub of a bicycle and rotatable with the wheel hub.
Conventional wheel frames for the bicycle are made of iron. An iron wheel frame has a strong structure and a heavy weight. In order to reduce the weight, aluminum is lately used to make wheel frames. Conventional methods have difficulties in making aluminum alloy wheel frames and cutter wheels or disc wheels over 50 mm height.
Nowadays, bicycle designs trend toward making the bicycle lightweight. Carbon fiber composite materials that are harder and lighter than aluminum are used not only for making bicycle frames but also for the fabrication of wheel frames, for example, the aforesaid prior art hollow wheel frame is made using carbon fiber composite materials.
However, wheel frames of carbon fiber composite materials are commonly made using blow molding technology. Due to hollow structure, a carbon fiber composite wheel frame will break easily if the wall thickness is too thin. However, when increasing the wall thickness, the weight of the carbon fiber composite wheel frame will be relatively increased. Further, a composite wheel frame made by means of blow molding is somewhat soft, it cannot completely and effectively transfer the force or torque applied by the rider to the tire, further it can break easily when twisted.